Palatal tremor after brachial plexus anaesthesia

Abstract

Editor'Palatal tremor (PT) is a rare disorder characterized by rhythmic movement of the soft palate.1Deuschl G Mischke G Schenck E Schulte-Monting J Lucking CH Symptomatic and essential rhythmic palatal myoclonus.Brain. 1990; 113: 1645-1672Crossref PubMed Scopus (220) Google Scholar It can be distinguished into symptomatic and essential. In the first case, ear clicks can be present and palatal movements are due to involvement of the levator veli palatini within other clinical findings; olivary pseudohypertrophy at brain imaging can be found after a delay of 1–6 months.2Deuschl G Toro C Valls-Sole J Zeffiro T Zee DS Hallett M Symptomatic and essential palatal tremor. 1. Clinical, physiological, and MRI analysis.Brain. 1994; 117: 775-788Crossref PubMed Scopus (225) Google Scholar In essential PT, ear clicks are more present and often an early complaint, while the contractions are located in the tensor veli palatini muscle which is innervated by the trigeminal nerve, and imaging evaluation usually is normal.3Deuschl G Toro C Hallett M Symptomatic and essential palatal tremor. 2. Differences of palatal movements.Mov Disord. 1994; 9: 676-678Crossref PubMed Scopus (69) Google Scholar Pathological studies outlined a role of the dentato-rubral-olivary pathway. Regarding drug-induced hyperkinetic movement disorders, the association with anaesthetics has already been reported for spinal myoclonus. We now report the first case of PT after brachial plexus levobupivacaine administration. A 49-yr-old woman came to our attention with a 2 month history of ear clicking sounds associated with involuntary movements of the soft palate. She complained of symptoms a few hours after a brachial plexus levobupivacaine 0.5% injection for surgery of the ulnar collateral ligament. Physical examination showed intermittent bilateral rhythmic activity of the palatal musculature at rest, and unperceived bilateral higher rhythmic contraction of the chin muscles after voluntary activation. The palatal contraction could not be inhibited by external sensory stimuli, whereas chin contraction could be suppressed by selective tactile stimuli of the trigeminal area. The patient also complained of bilateral ear clicks. No other postoperative complications were documented. The remainder of the neurological and otorhinolarygological examinations were normal. The tremors did not amielorate after clonazepam and carbamazepine intake. Routine blood tests showed normal findings. Brain MRI performed at the onset and after 2 months were normal. EMG study of the mentalis muscle showed pseudorhythmic bursts of about 100 ms duration at 5–6 Hz during mouth opening, while bilateral concentric needle exploration of the levator veli palatini showed pseudorhythmic bursts of 200 ms duration at 0.8–1 Hz (Fig. 1). No abnormal muscle activity was recorded from other muscles. A broad neurophysiological evaluation was normal. As reported, the occurrence of hyperkinetic disturbances after spinal or epidural injection of local anaesthetics (i.e. spinal myoclonus), and also side-effects due to excessive dosage or inadvertent intravascular injection during local anaesthesia can present.4Alfa JA Bamgbade OA Acute myoclonus following spinal anaesthesia.Eur J Anaesthesiol. 2008; 25: 256-257Crossref PubMed Scopus (20) Google Scholar To the best of our knowledge, our case represents the first description of PT after anaesthetic drugs. Although the pathophysiology of drug-induced hyperkinetic movement disorders is unclear, some authors postulated a reduced activity of suprasegmental inhibitory descending pathways or increased excitability of facilitatory mechanisms due to central nervous system drug-related toxicity.5Rothwell JC Pathophysiology of spinal myoclonus.Adv Neurol. 2002; 89: 137-144PubMed Google Scholar In our case, the central generator is supposed to be located along the dentato-rubral-olivary connections, susceptible to drug toxicity and responsible of the PT; while the chin tremor may appear as a dystonic-like tremor reduced by tactile stimulation. Our case further suggests to consider anaesthetics as a possible cause of drug-induced hyperkinetic movement disorders, and PT as a rare complication of anaesthesia. None declared.